Tool turret

ABSTRACT

The invention relates to a tool turret comprising: a housing ( 10 ), for connection to a machine tool, an electric drive motor ( 28 ), a tool disc ( 14 ), which is mounted such as to rotate relative to the housing ( 10 ), about a longitudinal axis ( 34 ) and which may be fixed in selected angular positions, with recesses ( 16 ) for machining tools ( 18 ). At least one rotating machining tool ( 18 ) may be driven by the drive motor ( 28 ), using shafts ( 24, 30 ), running perpendicular to the longitudinal axis ( 34 ) and which represent the swivelling axis of the tool disc ( 14 ). The above is embodied with the electric drive motor ( 28 ) arranged within the tool disc ( 14 ) and the driveshaft ( 30 ) from the electric drive ( 28 ) aligned with the driveshaft ( 24 ) for the machining tool ( 18 ) or running parallel thereto, such that an economical drive design for machining tools on a tool turret is achieved, furthermore with a small installation volume.

[0001] The invention relates to a tool turret having a housing to be connected to a machine tool, with an electric drive motor and a tool disk which is mounted rotatably relative to the housing and which may be fixed in selectable angular positions, as well as recesses for machine tools, it being possible to drive at least one rotating machine tool by a drive motor by way of shafts extending perpendicular to the longitudinal axis which represents the pivot axis for the tool disk.

[0002] DE 40 18 543 C1 discloses a tool turret having a housing to be connected to the machine tool and the latter has an electric drive motor and a tool disk which is mounted rotatably relative to the housing and recesses for tools at least one of which is configured for rotatable mounting of the tool. The machine tool may be driven the drive motor by way of shafts which are interconnected by gearing. There is also provided a hollow column which is mounted concentrically with the axis of rotation of the tool disk and which has at least one line which is included in a system provided for transmission of energy, lubricant, coolant, pressure means, or auxiliary forms of energy. The hollow column is immobile relative to the housing and one of the shafts driven by the drive motor is mounted in the hollow column and connected by the gearing to the other shaft by way of which the rotatably mounted tool may be driven when the recess into which this tool is introduced is in the operating position.

[0003] The tool turret disclosed provides a solution making it possible to transmit the auxiliary forms of energy or auxiliary means to the tool modules, tools, or the tools requiring such forms of energy, in a space conserving, problem-free, simple, and cost-effective manner. However, in that the disclosed drive system involves shafts and gearing, the disclosed tool drive configuration still requires much structural space and because of the large number of elements, which are also subject to wear, the disclosed solution is correspondingly cost intensive in production and a certain degree of maintenance must be provided.

[0004] DE 39 00 443 A1 discloses a variable-angle packaged unit for machine tools including turret heads, fixable cutters being retained in recesses which are mounted so as to be pivotable about a stationary table element along a longitudinal axis. In the disclosed solution two table elements of the turret head are mounted so as to be pivotable relative to each other around the longitudinal axis by way of an electric drive integrated into the tool disk, appropriate gearing down for the rotatable table element by way of a planet gear unit being possible. Driving of rotating machine tools is not possible with the disclosed solution.

[0005] DE 39 04 631 A1 discloses another turret head solution for machine tools, for turning machines in particular, an insertible rotating machine tool being driven by way of gearing and the drive shaft for the machine tool extending parallel to the main drive shaft for the turret head, itself in the form of a tool disk. In this disclosed solution the central electric drive is positioned outside the table unit proper of the tool disk, so that a compact structure is not possible with the solution disclosed. In addition, since the electric drive is separated a large axial distance from the tool disk driven by it plus together with the respective machining tool, inaccuracies in control of the structural components in question (disk, tool) are not to be excluded.

[0006] On the basis of this state of the art the invention has the object, while retaining the advantages afforded by the state of the art, of further improving the disclosed solutions so that they will be cost-effective in application, take up even less structural space, and permit reduction of maintenance costs as a result of increase in reliability of operation. The object as formulated in these terms is attained by a tool turret having the characteristics specified in claim 1 in its entirety.

[0007] In that, as specified in the characterizing part of claim 1, the electric drive motor is mounted inside the tool disk and in that the driven shaft of the electric drive is mounted so as to be aligned with or parallel to the drive shaft of the machining tool, the tool turret claimed for the invention suffices without costly shafts, the position of which is to be moved a number of times. The solution rather permits a direct drive configuration such that the driven shaft of the electric drive may operate in alignment with the drive shaft of the machining tool. The overall configuration, that is, drive motor with corresponding shaft elements, may be integrated as one packaged unit directly into the tool disk so as to conserve space, so that no structural space is required outside the tool disk. Consequently, Aslimline≅ exterior housing configurations may be achieved with the tool turret claimed for the invention; this represents an advantage especially in view of the restricted space available in the case of machine tools which may be outfitted with the widest possible variety of tools and tool groups. In addition, production and maintenance costs are reduced as a result of the restricted variety of elements. The direct drive configuration also ensures zero backlash, an aspect which on the whole promotes machining accuracy. The advantageous embodiments are also obtained if the driven shaft is mounted in parallel with the drive shaft. With an arrangement such as this there may be provided between the shafts a direct coupling or a gearing configuration, such as one in the form of toothed gearing for the purpose of transmitting the power output of the motor to the machine tool. In such a case the structure claimed for the invention is distinctly compact and “slim.≅

[0008] In one especially preferred embodiment of the tool turret claimed for the invention the electric drive is a brushless motor, an asynchronous motor or three-phase synchronous motor, preferably in the form of an interior rotor motor, in which the stator connected to the housing of the motor with the coil windings encloses the rotor with the magnet elements, the rotor being connected to the driven shaft of the electric motor. Electric motors used for this purpose have continuous speed controllable and the speed is a function of the frequency of the current supplied but otherwise more or less independent of the load, this an aspect of particular advantage for use with machine tools which may be subjected to varying loads during machining. In addition, such electric motors may be used to reach very high motor speeds, ones which may quite possibly range from 15,000 rpm to 80,000 rpm. The motors used for the purpose may be provided for direct driving of the machine tool and in addition are very compact, and yet because of their high speeds make high rated power available.

[0009] In another preferred embodiment of the tool turret claimed for the invention at least one gear unit, preferably a single-stage or multistage planet gear unit, reduction of the speed of the drive motor occurs between the driven shaft of the electric drive motor and the drive shaft of the machine tool. The planet gear unit in question permits distinctly space-saving and reliably operating reduction of the high speed requirement of the electric motor, so that a customary machining speed may be made available for the respective machine tool by the speed reduction by way of the planet gear unit. Provision is preferably made such that the driving gear of the planet gear unit is to be driven by the driven shaft of the electric drive motor, the drive wheel in turn driving at least one planet wheel of the gearing which always rolls along a stationary ringshaped gear housing element and the respective planet wheel transmitting the drive output arising during circulation of the planet wheel to the drive shaft of the machine tool by way of a carrier element (web).

[0010] Should additional speed reduction prove to be necessary, further provision may be advantageously made such that an additional planet gear unit is present along with the first, one whose drive wheel may be driven by the driven shaft of the first planet gear unit and whose output arising during circulation of its respective planet gear unit may drive the drive shaft of the machine tool. Even very high-speed three-phase synchronous motors may be stepped down by way of the two planetary gears to a nominal speed which may be classified as ideal for the drive of a machine tool. The speed in question may optionally be even further reduced by serial mounting of additional planet gear units, as a function of the machining speed it might be desired to make available for the tool.

[0011] In one preferred embodiment of the tool turret claimed for the invention a coupling system is provided between the driven shaft of the drive motor and the output in the form of a shaft of the respective planet gear unit mounted as last upstream from the drive shaft of the machine tool. The coupling system preferably may be controlled by way of a hydraulic operating system which in the coupled or uncoupled position drives the drive shaft of the machine tool for rotary propulsion of the machine tool or releases this shaft by means of the tool disk for a process of machine tool pivoting. The coupling system also makes it possible to release the machine tool in an extremely short time for a machine tool pivoting process and accordingly introduction of a new tool for immediate driving. Consequently, the introduction and replacement processes proceed very rapidly and every machine tool introduced as a replacement is immediately available for metal cutting.

[0012] In another especially preferred embodiment of the tool turret claimed for the invention the drive motor is mounted on a support on the side of the housing so as to be stationary, the tool disk with its tool recesses being pivotably mounted around the support. The support in question represents a sort of torque converter support, that is, the forces and possibly vibrations associated with the high torque values of the drive and transmitted to the drive housing are diverted to the other housing by way of the torque converter support. As a result, the electric drive motor with its very high speeds is reliably held on the housing side and in this way and is securely “anchored≅ for transmission of the high speeds.

[0013] In another preferred embodiment of the tool turret claimed for the invention the electric drive motor may be cooled by means of a cooling device whose coolant lines extend into the support of the housing. The cooling device used for the purpose makes it possible to control the amounts of heat associated with the high drive outputs, so that the machining accuracy is not impaired. Provision is preferably also made such that the hydraulic supply lines for the hydraulic operating device are mounted to extend at least to some extent into the support of the housing, as are also the lines for end position control of the coupling and/or operating device. In this way all relevant supply and energy lines may be incorporated by design by way of the support into the pivotable tool disk with its integrated drive configuration.

[0014] The tool turret claimed for the invention is explained in greater detail in what follows with reference to an embodiment as shown in the drawing, in which, in the form of diagrams not drawn to scale,

[0015]FIG. 1 presents, partly as a side view and partly as a longitudinal section, the tool turret with a machine tool introduced;

[0016]FIG. 2 a top view of planet gear unit with a driving or sun wheel and three planet wheels, the gears of which (not shown) roll along an external circumference mounted so as to be stationary;

[0017]FIG. 3 two serially mounted planet gear units (partly shown) as viewed along secant I—I in FIG. 2.

[0018] A tool turret has a housing 10 which is secured in position on a machine tool (not shown), for example, on a slide of such machine tool, by way of a threaded connection 12. There is mounted on one end of this housing 10 a tool disk (14) (tool carrier) rotatable relative to this housing, which tool disk has recesses 16 for machine tools 18 uniformly distributed over its circumference, tools which, configured as tool modules, have a rotating, metal cutting tool 20, for example, one in the form of a drill or milling cutter. In the exemplary embodiment the recesses 16 are in the form of drilled holes extending radially. A shank 22 of the machine tool may be inserted into each of these drilled holes, a drive shaft 24 projecting above such shank 22. The respective shank 22 may be provided on the external circumference side with positioning gearing (not shown in detail), so that in this way the machine tool 18 may always be secured in position in the recess 16 by way of a corresponding counterpart in the tool disk 14 as tensioning device. For the sake of simplification in presentation, only an inserted modular machine tool 18 has been shown in FIG. 1. The tensioning device in question has been disclosed in EP 0 585 600 B1, for example, and accordingly will not be described in greater detail at this point.

[0019] An electric drive motor 28 is mounted in the interior 26 of the tool disk 14. The driven shaft 30 of the electric motor 28, not shown in FIG. 1 and only indicated as an extension in FIG. 3, is in alignment with the drive shaft 24 along a common axis of rotation 32, which extends perpendicularly to a longitudinal axis 34 representing the pivot axis for the tool disk 14. In addition, the machining axis 36 for the metal cutting tool 20 is mounted either in parallel with the longitudinal axis 34 and perpendicularly to the axis of rotation 32 or in parallel with the axis of rotation 32 and perpendicularly to the longitudinal axis 34.

[0020] The electric motor 28 is mounted in a motor receptacle 38 as part of the housing 10. The motor receptacle in question 38 is mounted so as to be stationary and the tool disk 14 may assume a predetermined pivot position relative to this motor receptacle 38. The tool disk 14 has on its free frontal surface a front cover plate 40 which covers the motor receptacle 38 externally, the inner drive configuration being readily accessible from the exterior when the plate 40 is removed; this feature distinctly facilitates any maintenance and repair operations.

[0021] The three-phase electric motor 28 is a three-phase synchronous motor with a very high speed, 15,000 rpm, for example. The respective motor is preferably in the form of an internal armature motor in which the stator (not shown) with coil windings connected to the housing of the motor 28 encloses the rotor (not shown) with the magnet elements connected to the driven shaft 30 of the electric drive motor 28.

[0022] In order to reduce appreciably the high speed in question of the electric drive motor 28 for the machine tool 18, a reduction gear, preferably in the form of planet gear unit 42 is provided between the driven shaft 30 of the electric drive motor 28 and the drive shaft 24 of the machine tool 18 (see FIG. 2). The drive wheel 44 of the planet gear unit 42 may be driven by the driven shaft 30 of the electric drive motor 28 (see FIG. 3). For this purpose the driven shaft 30 extends through the gear housing 46 of the planet gear unit 42 for direct driving of the drive wheel 44. The drive wheel in turn drives three planet wheels 48, only planet wheel 48 shown as being uppermost in FIG. 2 being shown in FIG. 3. The three planet wheels 48 in turn all roll along the stationary annular gear housing 46. For this purpose the gear housing 46 has on its inner circumference gearing to which may be mated the teeth of the planet wheels 48. Similarly, the drive wheel 44 with its external gearing is mated to the three planet wheels 48.

[0023] The respective planet gear unit is of conventional design, and so will not be discussed in greater detail at this point; the operation of the planet gear unit 42 will be explained only to the extent necessary for understanding of the present invention. The planet wheels 48 in turn have central shafts 50 which are engaged in a carrier element 52, also termed “web≅ in technical language. The three carrier elements 52 are all guided rotatably in the central shafts 50 and otherwise bent twice at an angle (FIG. 3) in order to transmit the rotary movement of the planet wheels 48 to a common driven end 54 of the planet gear unit 42. The driven end 54 is in turn engaged in the gear housing 46 for the torque transmission in question. If the respective driven end is connected directly to the drive shaft 24 of the machine tool 18, the speed of the drive motor 28 may be reduced by a factor of 5, so that 3000 rpm are obtained for the machine tool 18. Since the speed of the drive motor 28 is continuously variable, the respective speed reduction of the machine tool 18 may be predetermined over a wide range.

[0024] If the electric motor 28 generates higher speeds, which quite possibly may range from 50,000 rpm to 80,000 rpm, the provision may be made for coupling the first planet gear unit 42 to a second planet gear unit 56, as is shown in diagram form in FIG. 3. The driven end 54 of the first planet gear unit 42 is guided to the input side 58 of the second planet gear unit 56 and the drive wheel 44 of the second planet gear unit 56 is thus driven. This second drive wheel 44 then transmits its rotary movement to the planet wheels 48 of the second gearing 56, further driven end 60 being transmitted to the drive shaft 24 of the machine tool 18 by way of the carrier elements or webs 52. The configuration shown in FIG. 3 may optionally be further supplemented by serial mounting of the planetary gears not shown, so that the speed of the electric motor 28 may be reduced in this way in specific stages. Very good speed reduction accompanied by saving of space may be achieved with the planet gear unit 42 and 56. It is also possible, however, to reduce the speed correspondingly in this instance with other sets of reduction gearing. Since in the solution illustrated all shaft elements 30, 54, 60, and 24 are aligned with each other, specifically, relative to the axis of rotation 32, unbalance problems are largely prevented and quiet operation of the drive configuration free of vibration is made possible.

[0025] As is illustrated in FIG. 1 in particular, a coupling device 62 designated as a whole as 62 is provided between the wavelike driven end 60 of the shaft and the drive shaft 24 of the machine tool 18. The respective coupling device 62 is actuated by a hydraulic or pneumatic operating device 64, the coupled position being shown in FIG. 1. The operating device 64 has two annular fluid chambers 66 and 68; in the coupled position shown in FIG. 1 the lower fluid chamber 68 is under pressure applied by a pressure medium, while the upper fluid chamber 66 is more or less kept free of pressure other than pressure of surrounding air. In the respective pressure application situation the coupling sleeve 70 is in its upper position as shown in FIG. 1; it entrains a coupling element 72 which has the function of effecting the coupling process itself. A connecting device 74 with a ball or roller bearing 76 is provided for the respective entrainment movement of the coupling sleeve 70 with coupling element 72. The ball bearing 76 in question makes it possible to position the coupling element 72 rotatably in the sleeve 70 with the coupling sleeve 70 mounted so as to be stationary. Such positioning is necessary to make it possible for the coupling element 72 to transmit the rotary movement of the driven end 60 of the shaft to the drive shaft 24 of the machine tool 18.

[0026] For the purpose of entraining the drive shaft 24 of the machining tool 18 this drive shaft has on its external circumference toothing 78 for mating to interior toothing of the coupling element 72. This coupling element 72 has on its upper side as seen in the line of sight to FIG. 1 a recess 80. A corresponding recess 82 is also present on the opposite side of the coupling element 72 so that the exterior toothing 84 may mesh with the interior toothing 86 of the coupling element 72. The interior toothing 86 in question is present only in the area of the lower free end of the coupling element 72. In addition, the structural depth of the recess 82 is designed so that, when the coupling element 72 is lowered over the coupling sleeve 70, the driven end 60 of the shaft may enter the second recess 82 and remain until the drive shaft 24 of the machining tool 18 has been withdrawn and has fully cleared the recess 80.

[0027] For the purpose of effecting the lowering movement in question the fluid chamber 66 is then to be pressurized and the level of pressure in the fluid chamber 68 lowered to the ambient pressure level. The operating device 64 then forces the coupling element 72, by way of the coupling sleeve 70 as thus pressurized, from its upper position as seen in the line of sight to FIG. 1 into its lower position (not shown). In this lower position the drive shaft 24 of the machining tool 18 is then freed and the tool disk 14 may be pivoted by appropriate actuation about its longitudinal axis 34 until another machining tool positioned in another recess 16 replaces the machining tool 18 shown. By reversal of the fluid control process for the chambers 66, 68 the coupling element 72 may then be returned by way of the coupling sleeve 70 to its coupling position and the output of the motor 28 may then be transmitted to the machining tool 18 when the coupling is effected. The coupling sleeve is in any event appropriately sealed on the inside and outside to prevent undesirable fluid escape. In order for the coupling element 72 to be able to rotate and still effect axial longitudinal displacement along the axis of rotation 32, a needle bearing cage 88 is mounted on the outer circumference side of the coupling element 72.

[0028] As has already been stated, the electric drive motor 28 is retained in a motor receptacle 38 which in turn is connected to a support 90 as a torque support. The rod-shaped support 90 accordingly carries on its free end the motor receptacle 38 on the upper side of which the coupling device 62 is mounted and is integrated into the housing 10, especially in the area of its other end. The electric drive motor 28 is enclosed in a cooling device 92 the coolant lines 94 of which extend into the support 90. The heat levels accompanying the high specific performance levels may be reliably removed from the motor receptacle 38 and accordingly from the tool disk 14 itself by way of the cooling device 92 question. The supply lines 96 for the operating device 64 also extend into the support 90. In addition, an end position switch 98 the transmission line 100 of which also extends into the support 90 is also provided for monitoring the operating situation of the coupling sleeve 70 or for the coupling element 72. Consequently, all essential supply and information lines are carried centrally by way of the support 90 into the interior of the tool disk 14.

[0029] A compact drive solution is made available by the tool turret claimed for the invention, a solution characterized by very high drive output values and drive speeds. The speeds in question may be transmitted directly to a machining tool or suitably reduced by way of gear steps. Since all drive shafts are in alignment on a common axis, unbalance phenomena are prevented. Such prevention works to the advantage of accuracy of machining by machining tools. A slimline design is obtained and the structural space available in the tool disk is efficiently used as a result of integration of the drive configuration into the tool disk, on the housing side in particular. 

1. A tool turret having a housing (10) to be connected to a machining tool, an electric drive motor (28), a tool disk (14) which is mounted so as to be rotatable about a longitudinal axis (34) relative to the housing (10), which may be fixed in selectable angular positions, and which has recesses (16) for machining tools (18), it being possible to drive at least one rotating machining tool (18) by the drive motor (28) by way of shafts (24, 30) extending perpendicularly to the longitudinal axis (34) which represents the pivot axis for the tool disk (14), characterized in that the electric drive motor (28) is mounted inside the tool disk (14) and in that the driven shaft (30) of the electric drive (28) is aligned or extends in parallel with the drive shaft (24) of the machining tool (18).
 2. The tool turret as claimed in claim 1, wherein the electric drive motor (28) preferably is an asynchronous motor or rotating current synchronous motor, preferably configured as an internal armature motor in which the stator connected to the housing (10) of the motor (28) with the coil windings encloses the rotor with the magnet elements, which rotor is connected to the driven shaft (30) of the electric drive motor (28).
 3. The tool turret as claimed in claim 1 or 2, wherein at least one gear unit reducing the speed of the drive motor (28), preferably a single-stage or multi-stage planet gear unit (42, 56), is present between the driven shaft (30) of the electric drive motor (28) and the drive shaft (24) of the machining tool (18).
 4. The tool turret as claimed in claim 3, wherein the drive wheel (44) of the planet gear unit (42) may be driven by the driven shaft (30) of the electric drive motor (28), wherein the drive wheel (44) drives at least one planet wheel (48) which always rolls along a stationary annular gear housing (46), and wherein the respective planet wheel (48) transmits the output of the driven end (54) arising during circulatory movement of the respective planet wheel (48) to the drive shaft (24) of the machining tool (18) by way of a carrier element (52).
 5. The tool turret as claimed in claim 4, wherein an additional planet gear unit (56) is provided the drive wheel (44) of which may be driven by the driven shaft (54) of the first planet gear unit (42) and the output of the driven shaft (60) of which arising during circulatory movement of its respective planet wheel (48) drives the drive shaft (24) of the machining tool (18).
 6. The tool turret as claimed in one of claims 1 to 5, wherein a coupling device (62) is provided between the driven shaft (30) of the drive motor (28) or the driven shaft end (54 or 60) of the planet gear unit (42 or 56) mounted as the last in advance of the drive shaft (24) of the machining tool (18).
 7. The tool turret as claimed in claim 1, wherein the coupling device (62) may be actuated by way of a hydraulic or pneumatic operating device (64), and, when in the coupled or uncoupled position, drives the drive shaft (24) of the machining tool (18) to rotate this machining tool (18) or releases it by means of the tool disk (14) for a process of pivoting of the machining tool (18).
 8. The tool turret as claimed in one of claims 1 to 7, wherein the electric drive motor (28) is mounted so as to be stationary on a support (90) in the form of housing, about which support (90) the tool disk (14) with its recesses (16) may be pivoted.
 9. The tool turret as claimed in claim 8, wherein the electric drive motor (28) may be cooled by a cooling device (92) the coolant lines (94) of which extend into the support (90) of the housing (10).
 10. The tool turret as claimed in claim 8 or 9, wherein the supply lines (96) for the operating device (64) extend at least to some extent into the support (90) of the housing (10), as do also the lines (100) for end position monitoring (98) of the coupling (62) and/or operating device (64). 